John Locke Theory of the Mind used a conceptual framework based on engrams (1690)
The engram is the medium by which information exctracted from past experience is transmitted to the computations that inform future behaviour. It is the physical trace of a memory.
We understand stored representations, which form the basis of the langage, even less than neuromorphic computations.
The information-conveying symbols in the engram are rapidly generated in the course of computations, which implies they are molecules.